This invention relates to the formation of three-dimensional objects on substantially a layer-by-layer basis with enhanced resolution. Preferred embodiments of the invention more particularly relate to controlling the drop volume in a selective deposition modeling environment.
Related Art
Rapid Prototypying and Manufacturing (RPandM) is the name given to a field of technologies that can be used to form three-dimensional objects rapidly and automatically from three-dimensional computer data representing the objects. RPandM can be considered to include three classes of technologies: (1) Stereolithography; (2) Laminated Object Manufacturing; and (3) Selective Deposition Modeling.
The stereolithography class of technologies creates three-dimensional objects based on the successive formation of layers of a fluid-like medium adjacent to previously formed layers of medium and the selective solidification of those layers according to cross-sectional data representing successive slices of the three-dimensional object in order to form and adhere laminae. One specific stereolithography technology is known simply as stereolithography and uses a liquid medium which is selectively solidified by exposing it to prescribed stimulation. The liquid medium is typically a photopolymer and the prescribed stimulation is typically visible or ultraviolet electromagnetic radiation. Liquid-based stereolithography is disclosed in various patents, applications, and publications of which a number are briefly described in the Related Applications section hereinafter. Another stereolithography technology is known as Selective Laser Sintering (SLS). SLS is based on the selective solidification of layers of a powdered medium by exposing the layers to infrared electromagnetic radiation to sinter or fuse the particles. SLS is described in U.S. Pat. No. 4,863,538 issued Sep. 5, 1989 to Deckard. A third technology is known as Three-dimensional Printing (3DP) 3DP is based on the selective solidification of layers of a powdered medium which are solidified by the selective deposition of a binder thereon. 3DP is described in U.S. Pat. No. 5,204,055 issued Apr. 20, 1993 to Sachs. Another technique is called Multijet Modeling, MJM, and involves the selective deposition of droplets of material from multiple ink jet orifices to speed the building process. MJM is described in PCT Publication Nos. WO 97-11835 published Apr. 3, 1997 naming Leyden as an inventor and WO 97-11837 published Apr. 3, 1997 naming Earl as an inventor (both assigned to 3D Systems, Inc. as is the instant application).
Laminated Object Manufacturing, LOM, techniques involve the formation of three-dimensional objects by the stacking, adhering, and selective cutting of sheets of material, in a selected order, according to the cross-sectional data representing the three-dimensional object to be formed. LOM is described in U.S. Pat. No. 4,752,352 issued Jun. 21, 1988 to Feygin; and U.S. Pat. No. 5,015,312 issued May 14, 1991 to Kinzie, and in PCT Publication No. WO 95-18009 published Jul. 6, 1995 naming Morita as an inventor.
Selective Deposition Modeling, SDM, involves the build-up of three-dimensional objects by selectively depositing solidifiable material on a lamina-by-lamina basis according to cross-sectional data representing slices of the three-dimensional object. One such technique is called Fused Deposition Modeling, FDM, and involves the extrusion of streams of heated, flowable material which solidify as they are dispensed onto the previously formed laminae of the object. An example FDM process is described in U.S. Pat. No. 5,121,329 issued issued Jun. 9, 1992 to Crump. Another technique is called Ballistic Particle Manufacturing, BPM, which uses a 5-axis, ink-jet dispenser to direct particles of a material onto previously solidified layers of the object.
Example BPM processes are described in PCT publication numbers WO 96-12607 published May 2, 1996 listing Brown as an inventor; WO 96-12608 published May 2, 1996 listing Brown as an inventor; WO 96-12609 published May 2, 1996 listing Menhennett as an inventor; and WO 96-12610 published May 2, 1996 listing Menhennett as an inventor, all assigned to BPM Technology, Inc.
Preferred embodiments of the present invention are primarily directed to Selective Deposition Modeling methods, systems, and apparatuses. Specifically, embodiments of the present invention involve dispenser control for controlling the drop volume of a dispensed droplet of solidifiable material. Since the layers comprise droplets, the volume of a droplet is related to the volume of the layer. Several features of the Selective Deposition Modeling techniques are related to the volume of the layer.
Exemplary features are the time required for the layer to solidify or freeze, the cooling requirements of the layer, and the ease of welding numerous layers together. When dispensing layer after layer of solidifiable material, the dispenser may be required to wait between layers, to allow the most recently formed layer to sufficiently freeze before dispensing the next layer. For layers with large volumes, the dispenser may have to wait a long time until the previous layer freezes. For example, assume that one layer has a large volume and another layer has a small volume. Assuming both layers have the same properties (e.g., dispensing temperature, heat conductivity, freezing point, and support temperature, etc.) the layer with the larger volume will take longer to solidify than the layer with the smaller volume. To reduce the time required for the layer with the larger volume to solidify, cooling devices could be used to cool the layers. With regard to welding, sometimes the ability to unite layers is hampered when the volume of one layer is significantly larger (or smaller) than the volume of the other layers.
A technique used in Selective Deposition Modeling systems previously manufactured by 3D Systems, Inc. (the Assignee of the present invention) for controlling the drop volume of a dispensed droplet of solidifiable material, employed randomly controlling the jets. In particular, a print head was supplied hot melt material in a flowable state from a reservoir for selective jetting from the print head. The jets on the print head were computer controlled to selectively emit droplets of molten material when each orifice (i.e., jet) was appropriately located at desired locations of a build platform. The drop volume capability of each jet was also computer controlled. Specifically, a random number of jets was selected and the drop volume capability of the selected jets was controlled to produce a droplet that had a pre-determined volume. For a single layer, this technique tended to produce a uniform drop volume within 10%. However, amongst layers, the drop volume was uniform approximately once every fifty layers.
It is an object of the present invention to provide simplified techniques (methods, systems, and apparatuses) for forming a three-dimensional object on a layer-by-layer basis by controlling the volume of a layer (or layers).
According to a first embodiment of the invention, a method, system and apparatus for forming a three-dimensional object on a layer-by-layer basis involves forming a portion of the three-dimensional object using Selective Deposition Modeling (SDM). Selective Deposition Modeling involves using at least one orifice, such as a jet, which dispenses a droplet of a flowable material that solidifies upon being dispensed. A drop volume capability of each orifice is adjusted until substantially all orifices have a uniform drop volume capability and all dispensed droplets of the flowable material have a uniform volume.
According to a second embodiment of the invention, a method, system, and apparatus for forming a three-dimensional object on a layer-by-layer basis also involves forming a portion of the three-dimensional object using selective deposition modeling, wherein at least one orifice is used. A first region of the formed portion is created, wherein the first region has a first deposition height and a first area deposition, A second region of the formed portion is created, wherein the second region has a second deposition height and a second area deposition. The first area deposition is different than the second area deposition. A drop volume capability of each orifice is adjusted until the first deposition height and the second deposition height are uniform.
According to a third embodiment of the invention, a method, system, and apparatus also involves forming a three-dimensional object on a layer-by-layer basis using selective deposition modeling, wherein a dispenser is used. A first region of the formed portion is created using a first group of orifices, and a second region of the formed portion is created using a second group of orifices. A drop volume capability of the first group of orifices and a drop volume capability of the second group of orifices is adjusted until the deposition height of the first region and a deposition height of the second region are uniform. Additionally, a drop volume capability of the first group of orifices and a drop volume capability of the second group of orifices is controlled until all dispensed droplets of the flowable material have a uniform volume.
Other aspects of the invention supply apparatuses for implementing the method aspects of the invention noted above.
Additional aspects of the invention will be clear from the embodiments of the invention described below in conjunction with the Figures associated therewith. Further aspects of invention involve the practice of the above referred to aspects of the invention in combination with one another.